1. Field of the Invention
The present invention relates to a plasma display device having a plasma display panel and a method for driving the plasma display panel.
2. Description of the Related Art
Recently, a display device having a large screen and a reduced thickness has been demanded and various thin display devices have been put to practical use. An AC discharge-type plasma display panel (hereinafter, refer to as a PDP) has been noticed as one of such thin display devices. The PDP has a front transparent substrate serving as a display screen and a rear substrate. A plurality of row electrodes are formed on the front transparent substrate and a plurality of column electrodes are formed on the rear substrate so as to cross the plurality of row electrodes. Between the front transparent substrate and the rear substrate, a discharge space which is filled with a discharge gas is formed. Pixel cells serving as pixels are formed at respective intersections of the row electrodes and the column electrodes including the discharge space.
In order to perform a display with grayscale level luminance in such a PDP, grayscale driving is performed based on a sub-field method. For example, a method of grayscale-driving a PDP in which each of frames of an input video signal is divided to eight sub-fields, and a full-scale write period, a full-scale erasure period, an address period, and a sustain discharge period are provided for each sub-field has been suggested (for example, see FIG. 5 in Japanese Patent No. 2756053). At this time, in the full-scale write period, a predetermined amount of wall charges is formed in all pixel cells by forcibly causing write discharge in all pixel cells. Further, through the write discharge, priming particles by the amount required for causing discharge in the address period described later are formed in all pixel cells. Specifically, the write discharge caused in the full-scale write period is referred to as initialization discharge through which the priming particles for surely causing discharge in each address period are formed and the amount of the wall charges over all pixel cells are uniform. Next, in the full-scale erasure period, the wall charges formed in all pixel cells are erased by causing erasure discharge with respect to all pixel cells. In the address period, the write discharge is selectively caused with respect to each of the pixel cells according to display data and the wall charges are formed in only pixel cells to be turned on. Then, in the sustain discharge period, sustain discharge is repeatedly performed with respect to only pixel cells in which the wall charges are formed, by the number of times assigned to each of the sub-fields. By driving in such a manner, a display is performed with a grayscale level luminance corresponding to times the sustain discharge is caused in each of the eight sub-fields.
However, since the light emission due to the initialization discharge (write discharge) caused in the full-scale write period has no relation with an actual display image, contrast at the time of displaying a relatively dark image, that is, dark contrast is deteriorated. Accordingly, a driving method in which the full-scale write period is provided in only a head sub-field of each of the eight sub-fields and the initialization discharge is caused in the full-scale write period of the head sub-field so as to suppress dark contrast from deteriorating has been suggested (for example, see FIG. 2 in Japanese Patent No. 2756053).
However, when the number of times of the initialization discharge in a display period of one field (frame) is simply reduced, the priming particles in each pixel cell become insufficient. Therefore, there is a problem in that the selective discharge may be not surely caused in the address period and an image quality may be deteriorated.